Vision is dependent upon the eye forming an image of an object and sending that image to the sensory centers of the brain. In this process, light reflected from an object passes through the cornea, the aqueous humor, the pupil, the lens and the vitreous humor of the eye. The reflected light is focused by the lens onto the retina, thereby stimulating the optic nerve cells. In turn, the optic nerve carries messages from the nerve cells to the visual cortex of the brain. The disc-shaped lens of the eye performs the same function as the lens of a camera.
The lens, as well as other internal parts of the eye, is subject to damage by physical or other external trauma, whether accidental or otherwise, and also by the formation of cataracts. Damage to the lens can affect its accuracy in focusing light on the retina. Damage to other internal parts of the eye can also effect the ability of the eye to accurately convert light into messages for transmission to the brain.
The formation of cataracts are a common disorder of the eye, and are one of the leading causes of blindness in the United States. A cataract is a physical change in the lens characterized by a transformation of the normally transparent lens to a cloudy or opaque state. As a consequence, adequate light cannot reach the retina, and vision becomes increasingly blurred. There are several basic types of cataracts, including congenital cataracts, cataracts caused by accidental injury, cataracts caused by disease such as diabetes or glaucoma, and so-called senile cataracts which commonly appear in persons over about 65 or 70 years of age.
Lens deficiencies, such as cataracts, and other internal eye problems are generally treated by surgical procedures in which an opening is made into the eye through which other surgical procedures such as removal of the damaged lens or other repair procedures can be carried out. A number of surgical procedures to create an opening for removing a damaged lens and replacing it with an artificial lens are known. The most frequently employed and favorably regarded methodology is the extracapsular technique wherein a transverse incision is made in the limbus zone directly through the cornea into the anterior chamber. One of the major advantages of this technique is that a small incision of only about 3 mm is required to remove the natural lens from the eye and insert an artificial lens. There are, however, a number of significant disadvantages associated with the use of this type of procedure.
Specifically, transverse incisions typically require the use of a number of sutures, which can result in additional discomfort and irritation during the healing process as well as induced astigmatism. It has been discovered that the size of the incision as well as suture tension will effect the severity of any resulting astigmatism. Moreover, a significant amount of undesirable drag on the incision edges during instrument insertion has been evident.
Consequently, a need exists for a surgical procedure to create an opening in the eye utilizing a minimum length incision together with a minimum number of sutures. Such a procedure has been developed and is particularly described in my copending application identified as Attorney Document No. SIEP-1 filed concurrently herewith and incorporated herein by reference. That procedure generally involves making a radial incision into the sclera, which incision is of a depth less than the scleral thickness, the creation of a subsurface scleral pocket both laterally and inferiorly to the radial incision and the making of a transverse incision in the subsurface pocket through the cornea and into the anterior chamber. Unfortunately, currently existing surgical knives and blades are unsuitable and/or inefficient for performing this surgical procedure. Consequently, a need exists for surgical blades which are capable of creating such an opening.